I dont hang around this forum that much, so dont flip out when I ask this. I just had a simple question. When I am spotting, I noticed that ASMD-80's take much less runway than AAMD-80's, even when both planes are full. Why is this, do they use different engines?

Heres some examples.

This Alaska MD-83 uses maybe half of the runway.

These American MD's use about 3/4's of it (a few times Ive seen rotations only 500 ft from the end of the runway).

If you are spotting from PDX, it's probably because the AA aircraft are used on longer routes. Therefore, they need more fuel, which adds weight and makes for a longer take-off roll. AA flies to ORD and DFW, which are farther than any destination AS serves directly from PDX with a Mad Dog, I believe.

Quoting TrijetsRMissed (Reply 1):If you are spotting from PDX, it's probably because the AA aircraft are used on longer routes. Therefore, they need more fuel, which adds weight and makes for a longer take-off roll. AA flies to ORD and DFW, which are farther than any destination AS serves directly from PDX with a Mad Dog, I believe.

Quoting TrijetsRMissed (Reply 1):If you are spotting from PDX, it's probably because the AA aircraft are used on longer routes. Therefore, they need more fuel, which adds weight and makes for a longer take-off roll. AA flies to ORD and DFW, which are farther than any destination AS serves directly from PDX with a Mad Dog, I believe.

Very true. In addition the AA birds might be using a lower thrust setting, also for fuel conservation.

Well at least we can all take comfort in the fact that NW will never retire their DC-9s

Quoting Dinker225 (Reply 10):When offered, the AAMD-80's will sometimes take the shorter runway here in PDX. Always depends on the winds. They really use the entire runway when they use the shorter of the 2!

One doesn't need a computer to add, subtract, multiply or divide . It just makes it easier. We were manually charting reduced thrust takeoffs for B-727-100 and DC-9-10 using the very manual, very non-digital JT8D-1 through -7 engines. Can't speak for earlier jet ops like the 707 but tables and run-around graphs have been around longer than jets have. Pencils predate diodes.

Happiness is not seeing another trite Ste. Maarten photo all week long.

Way to go Captain Click! Put those young'uns in their place. I had to learn to do math with paper, pencil and the computer between my ears! You young'uns with your newfangled calcu-laters should try it .

Extra credit for anyone under the age of 50 who posts the original meaning of the word computer, with a brief explanation in your own words about why this is relevant to the discussion at hand.

[Edited 2008-04-29 08:01:50]

"There are no stupid questions, but there are a lot of inquisitive idiots."

Quoting Starlionblue (Reply 13):Extra credit for anyone under the age of 50 who posts the original meaning of the word computer, with a brief explanation in your own words about why this is relevant to the discussion at hand

well weren't the original computers just basically E6-B's or similar so I suppose a "computer" would simply be a device capable of semi-basic calculations. I could be way off but thats just a guess.

Quoting Starlionblue (Reply 13):Extra credit for anyone under the age of 50 who posts the original meaning of the word computer, with a brief explanation in your own words about why this is relevant to the discussion at hand.

Basically anything that can extrapolate or manipulate data within a given set of constants, variables, and parameters.

It is relevant because aircraft crews had most of the same options and abilities before FADECs, ADCs, FMS, EICAS, etc. The only difference is they had to apply a little more brain power and effort to achieve them. However these skills are still relevant because any man-made device can and will fail, leaving you with only your wits, skills, and that "computer between your ears".

Do I win?

Well at least we can all take comfort in the fact that NW will never retire their DC-9s

Oh noes, here comes the geek... "computer" is a 17th century english word for a person who performs mathmatical calculations. It can be traced backwards to the latin word "computare": To count. It's relevant to the discussion because in it's original definition, pilots are computers. [/geek]

Quoting MDorBust (Reply 16):Oh noes, here comes the geek... "computer" is a 17th century english word for a person who performs mathmatical calculations. It can be traced backwards to the latin word "computare": To count. It's relevant to the discussion because in it's original definition, pilots are computers. [/geek]

Aww crap I think I lose

Well at least we can all take comfort in the fact that NW will never retire their DC-9s

Quoting MDorBust (Reply 16):Oh noes, here comes the geek... "computer" is a 17th century english word for a person who performs mathmatical calculations. It can be traced backwards to the latin word "computare": To count. It's relevant to the discussion because in it's original definition, pilots are computers. [/geek]

Correct! Have a gold star.

"There are no stupid questions, but there are a lot of inquisitive idiots."